The present invention generally relates improvements in portable power tools, and more specifically to improvements that are particularly well suited for use with wood working power tools such as portable power planers.
Various power tools are used in woodworking in an effort to efficiently and accurately form workpieces to desired dimensions and with a desired surface finish. As is widely known, planing machines are often used for surface planing of wooden boards. A conventional planing machine typically includes one or more rotatably mounted cutting blades attached to a vertically movable carriage assembly. Also known are jointer machines which are typically used for the edge planing of wood. In certain applications, the functions of conventional planing machines and jointers are combined within a single unit commonly referred to as a jointer/planer machine.
In a typical wood planing machine, such as a surface planer, a selectively adjustable workpiece opening is defined between a carriage assembly and the planing surface of the base of the machine. The rotationally mounted blades are carried on the underside of the carriage assembly adjacent to the workpiece opening. The blades are adapted to remove a predetermined amount of material from the workpiece depending on the thickness of the workpiece and the height of the workpiece opening. The carriage assembly also usually includes one or more feed rollers which urge the workpiece through the workpiece opening during the operation of the wood planing machine.
In most applications, the carriage assembly of a wood planing machine is movably mounted to a plurality of support columns for movement with respect to the planing surface. Such movement of the carriage assembly adjusts the vertical dimension of the workpiece opening so as to selectively determine the amount of material to be removed from the workpiece. Alternatively, the carriage assembly may be fixed and the planing surface adjusted vertically with respect to the carriage assembly so as to adjust the vertical dimension of the workpiece opening.
In use, a workpiece is passed through the workpiece opening and a predetermined amount of material is removed from the surface of the workpiece adjacent the carriage assembly. Multiple passes of the workpiece through the workpiece opening are often necessary to obtain the desired thickness and surface finish. As with other woodworking operations, it is desirable that a planing machine accomplishes preparation with precision, repeatability and a high quality surface finish. In order to accomplish these goals, many of the planing machines of the prior art have relied on designs that utilize rather large and heavy components.
While such designs have proven to be acceptable for relatively large planing machines which are repositioned on a relatively infrequent basis, they have largely been inadequate for portable planing machines, due to their weight. Accordingly, there is a need in the art for a portable planing machine having a highly robust design that permits a workpiece to be prepared with precision, repeatability and a high quality surface finish.
In one preferred form, the present invention provides a base assembly for a power tool having a base structure, plate structure and a plurality of fasteners. The base structure is formed from a first material in a forming process selected from a group of forming processes consisting of casting, die casting and molding. The base structure has a body portion defines a support surface that is not continuous over its entire area. The fasteners couple the plate structure to the base structure such that the plate structure is supported by the support surface. The support surface is not machined prior to the coupling of the plate structure to the base structure and the base assembly is machined only after the plate structure has been coupled to the base structure to provide a flat reference surface.
In another preferred form, the present invention provides a planing machine having a base, a carriage assembly, a plurality of guide posts and an elevation mechanism. The carriage assembly rotatably supports a cutter head assembly in a spaced-apart relation to a reference surface formed onto the base. The guide posts are fixedly coupled to one of the base and the carriage assembly and include a threaded adjustment portion. The elevation mechanism has a plurality of nut devices and an adjustment device. Each nut device has at least one threaded structure that is threadably engaged to the adjustment portion of an associated one of the guide posts. The nut devices are coupled to and rotationally supported by the other one of the base and the carriage assembly. The adjustment device has an input member, which is rotatably supported by the other one of the base and the carriage assembly, and an output, which has at least one output member that rotates in response to rotation of the input member. The output engages the nut devices such that a rotational input to the input member is transmitted through the output to the nut devices to cause the threaded structures to rotate on the adjustment portion of the guide posts to thereby adjust a distance by which the cutter head assembly is spaced apart from the reference surface.
In another preferred form, the present invention provides a cutter head assembly for use in a planing machine having a cutter head, a pair of locators, a cutter blade and a blade binder. The cutter head is configured to be rotatably supported relative to a reference surface and includes a body and a rotational axis. The body includes a blade mounting surface. The locators are coupled to the cutter head and extend from the blade mounting surface. The cutter blade has a mounting portion and a tip portion. The mounting portion is generally flat and has plurality of first clearance holes, a first locating aperture and a second locating aperture. The first and second locating apertures are spaced apart from one another and configured to receive one of the pair of locators. The tip portion is fixedly coupled to an end of the mounting portion and includes an edge. The blade binder is fitted over the at least a portion of the cutter blade and includes a plurality of second clearance holes. The threaded fasteners extend through the first and second clearance holes and threadably engaged to the cutter head. The fasteners cooperate to generate a clamping force that is transmitted through the blade binder to fixedly but releasably couple the blade to the mounting surface of the cutter head. The locators and the first and second locating apertures cooperate to align the cutter blade to the cutter head such that the edge of the tip portion is spaced apart from the rotational axis of the cutter head by a predetermined distance.
In yet another preferred form, the present invention provides a cutter head assembly for use in a planing machine having a cutter head, a cutter blade and a keeper mechanism. The cutter head is configured to be rotatably supported relative to a reference surface and includes a body and a rotational axis. The body includes a longitudinally-extending blade aperture having a reaction wall, a locating member and a forward wall that tapers outwardly toward the outer perimeter of the body and rearwardly toward the reaction wall. The cutter blade has a mounting portion and a tip portion. The mounting portion is generally flat and has a first abutting surface, which is configured to abut the reaction wall, a second abutting surface and a recess, which is configured to engage the locating member. The tip portion is fixedly coupled to an end of the mounting portion and includes an edge. The keeper mechanism includes a keeper element having a first inwardly tapering sidewall and a second inwardly tapering sidewall. The keeper element is disposed within the blade aperture such that the first inwardly tapering sidewall abuts the second abutting surface and the second inwardly tapering sidewall abuts the forward wall. The locating member and the recess cooperate to locate the edge of the tip portion a predetermined distance apart from the rotational axis of the cutter head. Centrifugal force generated by the rotation of the cutter head operates to wedge the keeper element against the second abutting surface and the forward wall to fixedly secure the cutter blade to the cutter head.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.